feat(FN-005): implement frontend foundation with auth and routing

- Add OIDC authentication with PKCE flow
- Create dashboard shell with sidebar and header
- Implement project management UI (list, create, detail)
- Add tool spawn page with tool/project selection
- Create tool instance detail page with status and controls
- Set up React Router with route guards
- Add Zustand auth store and API client with types

apps/web/src/stores/auth.ts

@@ -0,0 +1,24 @@
+import { create } from 'zustand'
+import type { User } from '../types/api.ts'
+
+export type AuthState = 'loading' | 'authenticated' | 'unauthenticated' | 'error'
+
+interface AuthStore {
+  state: AuthState
+  user: User | null
+  error: Error | null
+  setState: (state: AuthState) => void
+  setUser: (user: User | null) => void
+  setError: (error: Error | null) => void
+  logout: () => void
+}
+
+export const useAuthStore = create<AuthStore>((set) => ({
+  state: 'loading',
+  user: null,
+  error: null,
+  setState: (state) => set({ state }),
+  setUser: (user) => set({ user, state: user ? 'authenticated' : 'unauthenticated' }),
+  setError: (error) => set({ error, state: 'error' }),
+  logout: () => set({ user: null, state: 'unauthenticated', error: null }),
+}))